"It was a very tough game for us. Sometimes after internationals you can be a bit slow to start, but I thought Cardiff were very well organised," Lampard told Sky Sports News.
"Having gone 1-0 down, it's a very good result for us. It is difficult, but we've got a big squad here. It's important that we try and stay fresh, the manager changes it sometimes.
"If you get a positive result internationally, which a lot of us did, you can bring that back with you. I think the main thing is focus and concentration. We want to stay at the top of the league, we don't want to lose ground."
Chelsea's next Premier League fixture sees them face title hopefuls Manchester City at Stamford Bridge next Sunday.